iPad train simulation apps

[Bayum]

I’m wondering if anyone can help me. One of the children in my current cohort is autistic, suffers from aspergers and a whole other range of needs falling under many umbrellas. Since coming back to school, their current obsession is trains, specifically ‘The Titfield Thunderbolt’ or something or other. I have some iPads in the class which the child uses as a reward at the end of the day, but I was wondering if there were any train simulator apps you could recommend? Ideally ones that have lots of freeware available as I don’t fancy forking out for payware. They’ve downloaded ‘Trainz’ I think, but it only offers instructional scenarios, so something more would be fantastic!